JP2010019113A - Device equipped with damper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit a thermal effect on a transmission mechanism caused by heat generated by a damper. <P>SOLUTION: An internal combustion engine is provided with the damper 50 reducing vibration by converting the vibration energy of vibration generated on a camshaft 22 of a valve gear to heat, and a driven sprocket 33 of the transmission mechanism 30 driving and rotating the camshaft 22 on a shaft end 22a of the camshaft 22 at a position putting a chain cover 40 covering the driven sprocket 33 therebetween in an axial direction. Consequently, a part between the damper 50 and the driven sprocket 33 is divided by the chain cover 40. The transmission mechanism 30 is disposed in an oil atmosphere in a chain chamber 17 formed of the chain cover 40, and the damper 50 including damper rubber 53 is oil-tightly isolated from the chain chamber 17 by the chain cover 40. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an apparatus including a rotating shaft that is rotationally driven by a transmission mechanism, and a damper that reduces vibration by converting vibration energy of the rotating shaft into heat. And this apparatus is an internal combustion engine, for example, and the said rotating shaft is a cam shaft of the valve operating apparatus of this internal combustion engine.

In an internal combustion engine, a damper provided on the camshaft of the valve gear converts the camshaft vibration energy into heat to reduce the vibration in order to prevent camshaft resonance in a specific rotational speed region. What has a damper elastic body is known. (For example, see Patent Document 1)
Also, a valve control device for an internal combustion engine is rotationally driven by a transmission mechanism having an endless transmission band such as a chain, and a phase control that is provided at an end of the cam shaft and changes the phase of the cam shaft relative to the crankshaft. It is also known that a mechanism and a damper provided in a phase control device are provided, and the damper converts vibration energy of the camshaft into heat to reduce vibration of the valve operating system. (For example, see Patent Document 2)
JP-A-2-218805 JP 2007-107507 (FIGS. 4 and 5)

When a damper that reduces vibration of a rotary shaft such as a camshaft of a valve gear device converts vibration energy into heat to reduce vibration, a transmission mechanism (for example, disposed near the damper by heat generated by the damper) The sprocket provided on the camshaft) may be heated. Therefore, it is necessary to take measures to suppress the temperature rise of the transmission mechanism in order to eliminate the influence of such heating, resulting in an increase in cost. Furthermore, the heat generated by the damper may affect the damper itself, which may reduce the durability of the damper.
Further, when the damper element of the damper has the damper rubber, and the transmission mechanism is disposed in the oil atmosphere for lubrication, it is necessary to prevent the damper rubber from being deteriorated due to contact with the oil. However, enclosing the damper with a dedicated cover increases the number of parts and increases the cost.

  This invention is made | formed in view of such a situation, and the invention of Claims 1-4 aims at suppression of the thermal influence with respect to the transmission mechanism resulting from the heat | fever which a damper generate | occur | produces. The invention described in claim 2 further aims to improve the durability of the damper by preventing the deterioration of the damper due to the oil while reducing the number of parts and the cost. The invention further suppresses an increase in the size of the device in the axial direction of the rotating shaft due to the arrangement of the damper in the damper chamber formed by the transmission cover, and promotes the release of hot air in the damper chamber to the outside. An object of the present invention is to suppress the thermal influence on the transmission mechanism and improve the durability of the damper. The invention according to claim 4 further achieves the above object in an internal combustion engine including a camshaft and a damper. And simplifies the shape of the transmission cover that forms the breather passage and the damper chamber in which the damper is disposed and the breather passage. For the purpose of theft.

The invention described in claim 1 includes a rotating shaft (22) that is rotationally driven by the transmission mechanism (30), a transmission cover (40) that covers the transmission mechanism (30), and vibrations that occur in the rotating shaft (22). And a damper (50) that reduces vibrations by converting vibration energy of the shaft to the rotary shaft (30) at a position where the damper (50) and the transmission mechanism (30) sandwich the transmission cover (40). 22) is a device in which the damper (50) and the transmission mechanism (30) are partitioned by the transmission cover (40).
According to a second aspect of the present invention, in the apparatus according to the first aspect, the transmission mechanism (30) is disposed in an oil atmosphere in a transmission chamber (17) formed by the transmission cover (40), and the damper ( 50) has a damper rubber (53) made of a rubber material and is isolated from the transmission chamber (17) in an oil-tight state by the transmission cover (40).
According to a third aspect of the present invention, in the apparatus according to the first or second aspect, the damper (50) is recessed toward the transmission mechanism (30) in the axial direction of the rotary shaft (22) and the transmission cover (40 ) And a damper chamber (59) formed by a damper cover (70) covering the recess (46). The damper cover (70) includes the damper chamber (70). 59) and vent holes (76, 77) that communicate with the outer space (So) outside the damper chamber (59).
According to a fourth aspect of the present invention, in the device according to the third aspect, the device is an internal combustion engine, the rotating shaft (22) is a cam shaft (22) of a valve gear, and the recess (46). The peripheral wall (62) is a passage wall of the breather passage (49) formed in the transmission cover (40).

According to the first aspect of the present invention, the heat effect of the heat generated in the damper on the transmission mechanism by heat radiation and heat transfer is suppressed by the transmission cover that partitions the damper and the transmission mechanism. In addition, since a transmission cover that covers the transmission mechanism is used as a member that partitions the damper and the transmission mechanism, a dedicated member for partitioning that is separate from the transmission cover becomes unnecessary, and the number of parts is reduced. Cost is reduced.
According to the second aspect of the present invention, by using the transmission cover for the transmission mechanism arranged in the oil atmosphere, the damper rubber is prevented from being exposed to the oil atmosphere, and the oil to the damper rubber is prevented. Adhesion is prevented. As a result, deterioration of the damper rubber due to oil is prevented, and the durability of the damper is improved.
According to the third aspect of the present invention, since the damper is disposed in the recess formed in the transmission case, the damper is prevented from greatly protruding from the transmission cover in the axial direction, and the device including the damper is axially arranged. Can be downsized. In addition, the heat generated by the damper is dissipated to the external space through the ventilation holes, so that the cooling of the damper is promoted, so that the heat generated by the damper is caused by heat radiation, heat transfer, and heat conduction, and the driven sprocket. The heat effect on 33 can be further suppressed, the heat effect on the transmission mechanism can be further suppressed, and the durability of the damper is improved.
According to the fourth aspect of the present invention, in the internal combustion engine including the camshaft and the damper, the effects of the first to third aspects are achieved, and further, the breather passage is formed by using the transmission cover, and the damper is disposed. Since the peripheral wall of the recess that forms the damper chamber serves also as the passage wall of the breather passage, the shape of the transmission cover that forms the damper chamber and the breather passage is simplified, and the cost of the transmission cover can be reduced.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
Referring to FIGS. 1 and 2, an internal combustion engine E as an apparatus to which the present invention is applied is a multi-cylinder four-stroke internal combustion engine mounted on a vehicle. A cylinder block 1 having a cylinder 5, a cylinder head 2 coupled to the upper end of the cylinder 5, a head cover 3 coupled to the upper end of the cylinder head 2, and a lower block coupled to the lower end of the cylinder block 1. 4 and an oil pan (not shown) coupled to the lower end portion of the lower block 4, an engine main body as an apparatus main body, a chain cover 40 coupled to the engine main body, and a valve Device (hereinafter, simply referred to as “valve device”).
In the embodiment, the vertical direction is a direction parallel to the cylinder axis Lc (that is, the cylinder axis direction). Further, the axial direction is a direction parallel to the rotation center line L2 of the cam shaft 22 as a rotation shaft provided with a damper 50 described later, and the radial direction and the circumferential direction are radial directions centered on the rotation center line L2. And circumferential direction.

In the crankcase constituted by the lower part 1a of the cylinder block 1, the lower block 4 and the oil pan, the lower part 1a and the lower block 4 have a crankshaft as an output shaft connected to each piston 6 via a connecting rod 7. 8 is rotatably supported.
For each cylinder 5, a combustion chamber 10 is formed between the piston 6 and the cylinder head 2 in the cylinder axis direction. The cylinder head 2 includes an intake port 11 and an exhaust port 12 that open to the combustion chamber 10, respectively. An intake valve 13 and an exhaust valve 14 are provided as engine valves that are opened and closed by a valve device to open and close the intake port 11 and the exhaust port 12, respectively.
The piston 6 is driven by the pressure of the combustion gas generated by the combustion of fuel in the combustion chamber 10 to reciprocate, and rotates the crankshaft 8 via the connecting rod 7.

  The valve operating device disposed in the valve operating chamber 16 formed by the cylinder head 2 and the head cover 3 includes an intake camshaft 21 and an exhaust camshaft that are camshafts as rotational shafts that are rotatably supported by the cylinder head 2. 22 and an intake camshaft 21 (not shown) as a cam follower driven by an intake cam (not shown) and an exhaust cam (not shown) as a valve-operating cam respectively included in the intake camshaft 21 and the exhaust camshaft 22; An exhaust rocker arm (not shown), a valve spring (not shown) that constantly urges the intake valve 13 and the exhaust valve 14 in the valve closing direction, and the valve operating characteristics of the intake valve 13 according to the operating state of the internal combustion engine E And a phase control mechanism 23 as a variable valve operation characteristic control mechanism. The intake cam shaft 21 having the intake cam and the exhaust cam shaft 22 having the exhaust cam respectively drive the intake valve 13 and the exhaust valve 14 through the intake rocker arm and the exhaust rocker arm.

  Each of the camshafts 21 and 22 rotated about the rotation center lines L1 and L2 parallel to the rotation center line Le of the crankshaft 8 is driven by a valve gear transmission mechanism 30 provided in the internal combustion engine E. 2 (a journal portion 22d of the exhaust camshaft 22 is shown in FIG. 2) and is rotatably supported by a cam holder 15 provided integrally with the cylinder head 2. The cam holder 15 includes a lower bearing portion 15a formed integrally with the cylinder head 2 and an upper bearing portion 15b coupled to the lower bearing portion 15a with a bolt.

The transmission mechanism 30 includes a drive sprocket 31 that is a drive rotator provided on the crankshaft 8, a driven sprocket 32 that is a driven rotator provided on the intake camshaft 21 via a phase control mechanism 23, and an exhaust camshaft. A driven sprocket 33 which is a driven rotating body provided in 22 and an endless chain 34 which is an endless transmission belt which is stretched over these sprockets 31 to 33 and transmits the driving torque of the driving sprocket 31 to each driven sprocket 32, 33. And a winding transmission mechanism. The camshafts 21 and 22 as driven rotational shafts are rotated at a rotational speed that is ½ of the rotational speed of the crankshaft 8 due to the driving torque of the crankshaft 8 as the driving rotational shaft transmitted through the transmission mechanism 30. Is driven to rotate.
The phase control mechanism 23 is provided on the shaft end 21a of the intake camshaft 21 that protrudes in the axial direction from the cam holder 15, and the driven sprocket 33 is the shaft end of the exhaust camshaft 22 that protrudes in the axial direction from the cam holder 15. It is provided on 22a and rotates integrally with the exhaust camshaft 22.

  The phase control mechanism 23 provided at the shaft end 21a of the intake camshaft 21 changes the phase of the intake camshaft 21 with respect to the phase of the crankshaft 8 and changes the opening / closing timing of the intake valve 13 to drive the sprocket. The relative rotational position of 32 and the intake camshaft 21 is changed. The phase control mechanism 23 is a hydraulic mechanism that uses oil discharged from the oil pump of the internal combustion engine E as hydraulic oil, and is controlled by a hydraulic control mechanism that includes a hydraulic control valve.

The transmission mechanism 30 and the shaft end portions 21a and 22a include end portions 1e, 2e, 3e, and 4e in the axial direction of the cylinder block 1, the cylinder head 2, the head cover 3, and the lower block 4, and the end portions 1e, 2e, 3e, 4e are arranged in a chain chamber 17 as a transmission chamber formed by a chain cover 40 as a transmission cover coupled in a sealed state.
The chain chamber 17 is a space where there is an oil atmosphere, which is air mixed with oil such as lubricated oil at the lubrication points such as the valve train and the transmission mechanism 30, and each of the sprockets 31 to 33 and the chain 34 are It is covered with a chain cover 40 in the axial direction and is placed in an oil atmosphere.
With the chain cover 40 as a boundary, the transmission mechanism 30 is disposed in the internal space Si of the internal combustion engine E, which is an inner space of the chain cover 40, and a damper 50, which will be described later, is provided in an external space So, which is an outer space of the chain cover 40. Be placed. The internal space Si includes a chain chamber 17 and a valve operating chamber 16, and the external space So includes a damper chamber 59 described later.

  The chain cover 40 is opposed to the outer peripheral edge portion 41 coupled to the end portions 1e, 2e, 3e, and 4e by a large number of bolts B1, and to the end portions 1e, 2e, 3e, and 4e and the transmission mechanism 30 in the axial direction. It has the opposing wall 42 which covers the part 1e, 2e, 3e, 4e and the transmission mechanism 30 from the axial direction outer side. The facing wall 42 is a stepped wall 43 which is a wall part forming a step in the axial direction, and the axially outward from the mating surface 41a (see FIG. 2) of the outer peripheral edge 41 by forming the stepped wall 43. A plurality of wall portions having different distances at the lower wall portion 44 and the higher wall portion 45. The high wall portion 45 projecting axially outward from the low wall portion 44 extends from the lower portion 1a of the cylinder block 1 to the cylinder block 1 and the cylinder head 2 along the outer peripheral edge portion 41i on the intake side, along with the cylinder head 2 and the head cover. 3 extends to the valve chamber 16.

Here, the axially outward direction is a direction in which the external space So, the damper 50 or the damper chamber 59 is located with respect to the chain cover 40 in the axial direction, and the axially inward direction is opposite to the axially outward direction. This is a direction in which the internal space Si including the transmission mechanism 30 or the chain chamber 17 is located with respect to the chain cover 40.
In the internal combustion engine E, when viewed from the axial direction, the side where the intake port 11 is located with respect to the cylinder axis Lc is the intake side, and the side where the exhaust port 12 is located is the exhaust side.

In the chain chamber 17, the high wall portion 45 locally forms a passage-like protruding space 17a that is a space portion that protrudes axially outward from the low wall portion 44 in the axial direction. The projecting space 17a extends from a crank chamber formed by the crankcase to the valve operating chamber 16, and constitutes a breather passage 49 that guides blow-by gas in the crank chamber into the valve operating chamber 16. Therefore, the high wall portion 45 and the step wall 43 constitute a passage wall of the breather passage 49.
The blow-by gas guided to the valve chamber 16 is guided to the intake device of the internal combustion engine E after oil is separated by a gas-liquid separator (not shown) provided in the valve chamber 16. It is mixed with the intake air and sucked into the combustion chamber 10 through the intake port 11.
In a portion where the breather passage 49 extends outside the chain 34 along the slack side 34a, the protruding space 17a and the slack portion 34a are so large that the flow of blow-by gas toward the valve operating chamber 16 is not inhibited by the slack portion 34a. Is preferably separated from each other.

The camshafts 21 and 22 each have a driving torque of the crankshaft 8 that rotationally drives the camshafts 21 and 22 via the transmission mechanism 30, and a spring force of the valve spring of the valve operating device. Including torsional vibration due to the fact that torque due to valve reaction force from intake valve 13 and exhaust valve 14 based on this periodically acts as external torque consisting of load torque and biasing torque for camshafts 21 and 22 Vibration occurs. When the torsional vibration frequency matches the natural frequency of the camshafts 21 and 22 at a certain engine speed of the internal combustion engine E, the camshafts 21 and 22 resonate. This resonance may generate vibrations of large amplitude in the driven sprockets 32 and 33 and hence the transmission mechanism 30, and as a result, excessive tension may be generated in the chain 34.
On the other hand, also in the transmission mechanism 30 composed of the sprockets 31 to 33 and the chain 34, a certain engine is caused by fluctuations in the driving torque of the crankshaft 8 and the external torque that periodically acts by the valve gear. Resonance may occur at the rotational speed, and in that case too much tension may be generated in the chain.

  Therefore, by preventing the occurrence of resonance of the cam shafts 21 and 22 due to torsional vibration and reducing the vibration of the transmission mechanism 30 due to the resonance, or by preventing the occurrence of resonance of the transmission mechanism 30 itself, In order to prevent the occurrence of excessive tension in the chain 34, the internal combustion engine E is mainly transmitted to the exhaust camshaft 22 from the aforementioned torsional vibration or the transmission mechanism 30 as vibration generated in the exhaust camshaft 22. A damper 50 for reducing vibration is provided. In this embodiment, the damper 50 is provided on the exhaust camshaft 22 which is one of the two camshafts 21 and 22, but may also be provided on the intake camshaft 21.

Referring also to FIG. 3, a damper 50 provided at the shaft end portion 22a of the exhaust cam shaft 22 and rotating integrally with the cam shaft 22 is connected to the shaft end portion via a cylindrical boss member 54 as a mounting member. To 22a. The boss member 54 is provided with an insertion hole 54a through which a bolt B2 as a coupling tool is inserted, and the boss member 54 coupled to the shaft end portion 22a by the bolt B2 rotates integrally with the cam shaft 22.
The boss member 54, which extends from the shaft end 22a and extends outward in the axial direction, passes through the through hole 48 provided in the chain cover 40 and crosses the chain chamber 17 and the damper chamber 59 in the axial direction. Arranged. The boss member 54 also serves as an axial stopper that contacts the driven sprocket 33 in the axial direction and prevents the driven sprocket 33 from moving in the axial direction.

  The damper 50 is press-fitted into the boss member 54 and arranged in a radially outward direction with respect to the boss member 54 and the sleeve 51, and an annular sleeve 51 as a mounting portion coupled to rotate integrally with the boss member 54. And an annular damper rubber 53 as a damper elastic body disposed between the sleeve 51 and the damper mass 52 in the radial direction. A damper rubber 53 made of a rubber material is fixed to the outer periphery of the sleeve 51 at its inner periphery by baking or bonding, and is fixed to the inner periphery of the damper mass 52 at its outer periphery by baking or bonding.

  A damper rubber 53, which is a damper element, reduces vibration of the cam shaft 22 by converting vibration energy of vibration generated in the cam shaft 22 into heat. Then, by appropriately setting the natural frequency of the damper 50, resonance of the cam shaft 22 or resonance of the transmission mechanism 30 can be prevented at a specific engine speed of the internal combustion engine E.

2 to 4, the damper 50 is disposed in a damper chamber 59 formed by a damper housing H provided in the chain cover 40. The damper housing H includes a damper case 60 formed by a part of the chain cover 40, and a damper cover 70 that is coupled to the damper case 60 by bolts B3 at its mounting seats 63a, 63b, and 63c.
The damper case 60 integrally formed with the chain cover 40 is configured by a recess 46 formed in the chain cover 40 so as to be recessed in the axial direction toward the driven sprocket 33 or the chain 34 (that is, inward in the axial direction).

The damper case 60 has an inner peripheral edge 61a that forms a circular through-hole 48 and a radial wall 61 that extends in the radial direction, and a peripheral wall 62 that extends axially outward from the outer periphery of the radial wall 61. And three mounting bosses 63a, 63b, and 63c that are connected to the peripheral wall 62 as a plurality of bosses. The radial wall 61 is a bottom wall of the damper case 60 (that is, the recess 46).
The peripheral wall 62 is a plurality of, in this case, two peripheral wall portions having different widths (or heights) in the axially outward direction from the radial wall 61 with the mounting seats 63a, 63b, and 63c as boundaries. It is comprised from the high surrounding wall part 62a and the low surrounding wall part 62b. The high peripheral wall 62a, which is higher than the low peripheral wall 62b, is constituted by a part of the step wall 43 and is located between the mounting seats 63a, 63b adjacent in the circumferential direction. The low peripheral wall portion 62b is located between the mounting seats 63b and 63c adjacent in the circumferential direction, and there is no peripheral wall 62 between the mounting seats 63a and 63c adjacent in the circumferential direction.

  A radial wall 61 that is a part of the chain cover 40 is disposed between the damper 50 and the driven sprocket 33 in the axial direction. An oil seal 55 is provided between the inner peripheral edge 61a and the boss member 54 in the radial direction as a seal member that seals between the inner peripheral edge 61a and the boss member 54 in an oil-tight manner. As described above, the damper 50 and the driven sprocket 33 of the transmission mechanism 30 are provided on the shaft end portion 22a of the exhaust cam shaft 22 side by side in the axial direction at a position sandwiching the chain cover 40 in the axial direction. Therefore, the chain cover 40 is disposed between the damper 50 and the driven sprocket 33, both of which are coupled to the shaft end 22a. As a result, the damper 50 and the transmission mechanism 30 or the driven sprocket 33 are partitioned by the chain cover 40, and the damper chamber 59 is isolated from the chain chamber 17 in an oil-tight state. Therefore, the damper 50 and the damper rubber 53 are in an oil-tight state. It is isolated from the transmission mechanism 30 or the driven sprocket 33.

  Referring also to FIG. 5, a bowl-shaped damper cover 70 that covers the damper case 60 from the axially outer side includes a radial wall 71 extending in the radial direction and an outer periphery of the radial wall 71 inward in the axial direction. A cylindrical peripheral wall 72 that extends, mounting portions 73a, 73b, 73c (see also FIG. 1) that are connected to the peripheral wall 72 and are the same number of bosses as the mounting seats 63a, 63b, 63c, and axially inward from the peripheral wall 72 One or more extended peripheral wall portions 74 (in this case, these are shown by two-dot chain lines in FIG. 4).

  The mounting seats 63a, 63b, 63c and the mounting portions 73a, 73b, 73c are arranged at equal intervals in the circumferential direction on a circumference having a diameter substantially equal to the outer diameter of the peripheral wall 72 around the rotation center line L2. . The damper cover 70 is coupled to the damper case 60 and thus the chain cover 40 by a bolt B3 that is inserted into each of the mounting portions 73a, 73b, and 73c and screwed into the corresponding mounting seats 63a, 63b, and 63c.

In this embodiment, the extended peripheral wall portion 74 is provided between the mounting portions 73b and 73c adjacent in the circumferential direction and between the mounting portions 73a and 73c, and between the mounting portions 73a and 73b adjacent in the circumferential direction. It is not provided in between. Accordingly, in the damper housing H, the damper 50 is covered from the outer side in the radial direction by the high peripheral wall 62a and the peripheral wall 72 between the mounting seats 63a and 63b or between the mounting portions 73a and 73b in the circumferential direction. Between the mounting seats 63b, 63c or between the mounting portions 73b, 73c, the bottom peripheral wall portion 62b, the peripheral wall 72, and the extended peripheral wall portion 74b are covered from the outside in the radial direction, and between the mounting seats 63a, 63c in the circumferential direction or the mounting portion 73a. , 73c is covered from the outside in the radial direction by the peripheral wall 72 and the extended peripheral wall portion 74c.
The damper 50 is covered with the damper cover 70 from the radially outer side and the axially outer side, so that other members are prevented from contacting the rotating damper 50 and the vibration reducing effect by the damper 50 is prevented from being hindered. The

  As described above, the extended peripheral wall portion 74 is an adjustment wall portion that can be removed or adjusted in width (projection amount) in the axial direction according to the height of the peripheral wall 62 of the damper case 60. For this reason, a damper cover (hereinafter referred to as “original damper cover”) in which extended peripheral wall portions 74 are provided at intervals in the circumferential direction between the mounting portions 73a, 73b; 73b, 73c; 73a, 73c adjacent in the circumferential direction. )) As a common damper cover, and depending on the shape of the peripheral wall 62 of the damper case 60 (that is, the recess 46) to which the original damper cover is attached or the shape of the chain cover 40, the extended peripheral wall of the original damper cover The chain cover 40 having different heights of the peripheral walls 62 of the damper case 60 can be obtained by removing the portions 74 for each of the extended peripheral wall portions 74 or by performing processing to adjust the width of the extended peripheral wall portion 74 in the axial direction. Can also be applied, so the cost of the damper cover can be reduced.

Referring also to FIG. 1, the damper cover 70 includes one or more ventilation holes 76 in this embodiment that form a ventilation path that connects the damper chamber 59 and the external space So outside the damper chamber 59. , 77 are provided. The ventilation holes 76 and 77 which are heat radiation holes for releasing the hot air in the damper chamber 59 to the external space So are one or more elongated holes formed in the radial wall 71 and formed radially in the radial direction, here. A plurality of radial slits 76, which are a plurality of radial vent holes, and one or more axial slits, here a plurality of axial vent holes, which are long long holes parallel to the axial direction in a circumferential wall 72 provided in the circumferential direction. 77. Each radial slit 76 is provided in the same radial range, and each axial slit 77 is provided in the same axial range.
The radial slits 76 and the axial slits 77 are formed to be spaced apart from each other at equal intervals in the circumferential direction, and the radial slits 76 and the axial slits 77 are formed to be spaced apart in the radial direction. . As described above, since the slits 76 and 77 are not connected to each other, the rigidity of the damper cover 70 is enhanced.

  As shown in FIGS. 1 and 5, the radial slit 76 is provided in a radial range substantially equal to the position of the damper 50 in the radial direction, and overlaps the entire damper rubber 53 and the entire damper mass 52 when viewed from the axial direction. Provided in position. With this structure, the heat generated by the damper rubber 53 is efficiently released outside the damper chamber 59 through the radial slit 76.

Next, operations and effects of the embodiment configured as described above will be described.
In the internal combustion engine E, a damper 50 that reduces vibration by converting vibration energy generated in the cam shaft 22 of the valve gear to heat, and a driven sprocket 33 of the transmission mechanism 30 that rotationally drives the cam shaft 22 include: The damper 50 and the driven sprocket 33 are partitioned by the chain cover 40 by being provided at the shaft end 22a of the cam shaft 22 at a position sandwiching the chain cover 40 covering the driven sprocket 33 in the axial direction. With this structure, the heat generated by the damper rubber 53, which is the damper element of the damper 50, is affected by the heat effect on the driven sprocket 33 of the transmission mechanism 30 by heat radiation and heat transfer, and the chain cover that partitions the damper 50 from the driven sprocket 33. 40 is suppressed. In addition, since the chain cover 40 that covers the transmission mechanism 30 is used as a member that partitions the damper 50 and the driven sprocket 33, a dedicated member for partitioning that is separate from the chain cover 40 becomes unnecessary. The number of parts is reduced and the cost is reduced.

  The transmission mechanism 30 is disposed in an oil atmosphere in the chain chamber 17 formed by the chain cover 40, and the damper 50 has a damper rubber 53 made of a rubber material, and the chain cover 40 in an oil-tight state from the chain chamber 17 By using the chain cover 40 against the transmission mechanism 30 disposed in the oil atmosphere due to the isolation, the damper rubber 53 is prevented from being exposed to the oil atmosphere, and oil to the damper rubber 53 is prevented. Is prevented from sticking. As a result, deterioration of the damper rubber 53 due to oil is prevented, and the durability of the damper 50 is improved.

  The damper 50 is formed in a damper chamber 59 formed by a recess 46 that is a damper case 60 formed in the chain cover 40 and is recessed toward the driven sprocket 33 in the axial direction of the cam shaft 22 and a damper cover 70 that covers the recess 46. The damper cover 70 is provided with a plurality of slits 76 and 77 that communicate the damper chamber 59 and the external space So outside the damper chamber 59, so that the damper 50 is a recess formed in the chain cover 40. Therefore, the damper 50 is prevented from greatly protruding from the chain cover 40 in the axial direction, and the internal combustion engine E including the damper 50 can be downsized in the axial direction. Moreover, since the heat generated by the damper 50 is radiated to the external space So through the slits 76 and 77, the cooling of the damper 50 is promoted, so that the heat generated by the damper 50 is heat radiation, heat transfer, The heat conduction through the boss member 54 or the shaft end portions 21a and 22a can further suppress the thermal effect on the driven sprocket 33 and improve the durability of the damper 50.

  Since the peripheral wall 62 of the recess 46 is a passage wall of the breather passage 49 formed in the chain cover 40, the breather passage 49 is formed by using the chain cover 40, and the damper chamber 59 in which the damper 50 is disposed is provided. Since the peripheral wall 62 of the recess 46 to be formed also serves as the passage wall of the breather passage 49, the shape of the chain cover 40 that forms the damper chamber 59 and the breather passage 49 is simplified, and the cost of the chain cover 40 can be reduced.

Hereinafter, a mode in which a part of the above-described embodiment is changed will be described focusing on the changed portion.
The damper may be provided on at least one of the intake cam shaft and the exhaust cam shaft. The valve gear may be provided with only one cam shaft.
The damper may be directly coupled to the camshaft.
The endless transmission band of the transmission mechanism may be a belt. The transmission mechanism may be configured by a gear train including a plurality of gears.
The damper case may have a peripheral wall continuous over the entire circumference. Further, the damper case may be a member that is separate from the chain cover and that is a member that becomes a recess recessed inward in the axial direction.
The damper element may use a shear resistance of a viscous fluid having a high viscosity.
The internal combustion engine may be a single-cylinder internal combustion engine or a V-type internal combustion engine, and may be used for a machine other than a vehicle. For example, a ship propulsion such as an outboard motor having a crankshaft oriented in the vertical direction. It may be used for an apparatus.
The device including the damper is the internal combustion engine in the above-described embodiment, but may be a device other than the internal combustion engine or a device including the internal combustion engine (for example, a generator). Further, the rotation shaft may be a rotation shaft other than the cam shaft.

(A) is the figure of the principal part which looked at the internal combustion engine to which this invention was applied from the axial direction, (b) is sectional drawing of the chain cover in the bb line of (a). It is the II-II sectional view taken on the line of FIG. It is the III-III sectional view taken on the line of FIG. It is a figure of the principal part of the chain cover in the IV-IV arrow view of FIG. It is a figure of the damper cover in the VV arrow view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Cylinder block, 2 ... Cylinder head, 17 ... Chain chamber, 21, 22 ... Cam shaft, 30 ... Transmission mechanism, 31-33 ... Sprocket, 34 ... Chain, 40 ... Chain cover, 46 ... Recessed part, 49 ... Breather passage 50 ... Damper, 59 ... Damper room, 70 ... Damper cover, 76,77 ... Slit,
E: Internal combustion engine.

Claims (4)

In an apparatus comprising: a rotating shaft that is rotationally driven by a transmission mechanism; a transmission cover that covers the transmission mechanism; and a damper that reduces vibration by converting vibration energy of vibration generated in the rotating shaft into heat.
The apparatus, wherein the damper and the transmission mechanism are provided on the rotating shaft at a position sandwiching the transmission cover, whereby the damper and the transmission mechanism are partitioned by the transmission cover. The transmission mechanism is disposed in an oil atmosphere in a transmission chamber formed by the transmission cover,
2. The apparatus according to claim 1, wherein the damper includes a damper rubber made of a rubber material and is isolated from the transmission chamber in an oil-tight state by the transmission cover. The damper is disposed in a damper chamber formed by a recess formed in the transmission cover that is recessed toward the transmission mechanism in the axial direction of the rotating shaft, and a damper cover that covers the recess,
The apparatus according to claim 1, wherein the damper cover is provided with a vent hole that communicates the damper chamber with an external space outside the damper chamber. The device is an internal combustion engine;
The rotating shaft is a camshaft of a valve gear;
The device according to claim 3, wherein the peripheral wall of the recess is a passage wall of a breather passage formed in the transmission cover.

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